Existing railroad locomotives are typically powered by diesel electric engines in which a diesel motor drives an electric generator to produce electric power to drive electric motors which in turn drive the drive wheels of the locomotive. The present inventor has disclosed the use of a gas turbine engine fueled by compressed natural gas in substitution for the traditional diesel engine in his U.S. Pat. No. 5,129,328 issued Jul. 14, 1992, and as a booster unit for the diesel engine in his U.S. Pat. No. 4,900,944 issued Feb. 13, 1990, both of which are incorporated herein by reference.
The use of energy storage batteries in combination with a generator is known for automobiles, buses and other road and highway vehicles. Such hybrid engines for vehicles are advantageous due to their increased fuel efficiency and reduced pollution. In those applications, it is important to minimize the weight of the batteries to maintain fuel efficiency. Electric batteries have been used to store electric power to drive electric locomotives as, for example, disclosed by Manns in U.S. Pat. No. 1,377,087 issued May 3, 1921 which is incorporated herein by reference. In Manns, three standard diesel engines are used to drive generators to charge the storage batteries. Such a system has not achieved commercial acceptance over existing diesel electric locomotives due to the added cost and complexity of providing multiple diesel engines in addition to the storage batteries.
The present inventor has also disclosed the use of a battery powered locomotive which has a ratio of energy storage capacity to charging power in the range of 6 to 40 hours in his U.S. Pat. No. 6,308,639 issued Oct. 30, 2001 which is also incorporated herein by reference.
The present inventor has also disclosed the use of individual chopper circuits associated with individual drive axles in his copending U.S. patent application Ser. No. 10,083,587 filed on Feb. 26, 2002.
There remains a need for a fuel-efficient locomotive which uses a combination of a small fuel-powered generator, a substantial energy storage capacity, and control systems that regulates and maintains the power train at maximum fuel efficiency and minimizes maintenance. Such control systems would also allow greater command over individual drive axles to help alleviate undesirable conditions such as non-synchronous wheel slippage and wheel locking.